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Quick Apps for Handhelds

Quick Apps are simple, finger-friendly engineering tools designed for use on any handheld phone or computer that supports Javascript. Just select a tool from the Quick Apps Menu. That's it.

Just click to get started. Select "Quick Apps", then select the tool you want to use. Enter numbers like on a calculator and then press the button for the parameter where you want that number copied. Calculations are automatic.

You can read more in the QuickApps Overview (pdf) presentation.

Things you can do


The Quick Apps are built upon variants of the RPN Calculator app so they all have a similar look and feel. Pressing number buttons form a number in the calculator's text field. Specialized apps, have additional text boxes for the relevant parameters along with special buttons to copy the calculator text field value to the parameter text field. These special parameter buttons copy the data and then update the computations. You can also enter numbers directly into text fields.

Reverse Polish Notation calculators have no "=" button. When you enter your first number of a calculation you then press the "ENT" (ENTER) button to save the number on the working stack. Enter your second number parameter and then press the desired operation. For example to add 3 and 5, press 3, press ENTER, press 5, and press +. Answer is 8.

Another example is computing sin(PI/4). Press PI button (this button also performs an ENTER operation). Press 4, press "/", press SIN. Answer is 0.707.

The "CLX" button is used to zero the calculator text field (referred to as X).

The basic calculator has one memory location in which you can store (STO) and recall (RCL) a constant.

The working stack has four levels. The calculator text field represents X. Any X value ENTered onto the stack is referred to as Y. To raise 2 to the 3rd power, press 3, press ENT, press 2, press "X^Y". Answer 8. You can exchange X and Y values with the "X:Y" button. Two exchanges (presses of the "X:Y" button) restore the original settings. You can rotate the four level stack through the calculator text field using the "Rv" button. Four rotations (presses of the "Rv" button restores the original stack values.

Calculator Button Summary

  • CLX - Clears the calculator text field to zero.
  • 0 to 9 - Buttons to enter digits to form a number.
  • CHS - Changes the sign of the number in the calculator text field.
  • ENT - ENTERs (stores) the calculator text field value onto the stack as Y specifying the first value of your computation.
  • "+, -, *, /" - Add, subtract, multiply and divide using the calculator text field value, X with the stack value Y resulting in Y+X, Y-X, Y*X, Y/X.
  • "." - Places a decimal point in the calculator text field number.
  • X:Y - Exchanges the current X (calculator text field) and Y (first stack entry) values.
  • Rv - Rotates the stack values. Four presses of the Rv button does a complete rotation.
  • STO - Stores the curreent calculator text field value in the one memory location.
  • RCL - Recalls the memory location value putting it into the current text field (X) and pushers it onto the stack (Y).
  • PI - Puts the value of PI (3.15159...) into the current text field (X) and pushers it onto the stack (Y).
  • SQRT - Computes the square root of the calculator text field X.
  • X^Y - Raises the calculator text field X to the power specified by the stack entry Y.
  • e^X - Raises the constant e (2.7182...) to the power specified by the calculator text field X.
  • LN - Computes the natural log (base e) of the calculator text field X value.
  • 10^X - Raises the constant 10 to the power specified by the calculator text field X.
  • LOG - Computes the log (base 10) of the calculator text field X value.
  • SIN - Computes the sine of the calculator text field X expressed in radians.
  • ASIN - Computes the angle in radians of the sine value in the calculator text field X.
  • COS - Computes the cosine of the calculator text field X expressed in radians.
  • ACOS - Computes the angle in radians of the cosine value in the calculator text field X.
  • TAN - Computes the tangent of the calculator text field X expressed in radians.
  • ATAN - Computes the angle in radians of the tangent value in the calculator text field X.

Ohm's Law App

Ohm's Law, E(the Voltage in Volts) = I (the current in Amperes) * R (the resistance in Ohms), is computed in the Ohm's Law App. Three extra text fields (E, I, R) appear under the calculator text field. Three additional buttons (E, I and R) are used to copy the number in the calculator text field to the corresponding E-I-R text field. This also causes the Ohm's Law computation to be updated. Normally you would enter two of the values to find the third.

Computations are updated when you change an E, I, or R text field either by a button or by direct entry to the text field. If you wish to pre-specify the item you wish to solve, first press the desired E, I or R button then press the SLV button.

Impedance App

Calculate parallel, series and voltage divider combinations of two impedances. You can specify the resistance and reactance values or enter values of R, L, C and frequency. A report widow summarizes the calculations and also presents magnitude and phase values.

Temperature App

Converting degrees Centigrade to Fahrenheit is easily done by entering the temperature into the the calculator text field and then pressing the C or F button to copy it into the appropriate temperature text field. Conversion occurs immediately.

Length App

Converting inches, feet, and miles into millimeters, centimeters and kilometers is easily done by entering the length into the the calculator text field and then pressing the standard button to copy it into the appropriate standard text field. Conversion occurs immediately. Change the specified units using the menu boxes.

db / dbm Conversions

Power measurements for audio and RF applications often use decibels, db, or dbm (decibels referenced to a milliwatt). Decibels (db) express a power ratio either between two power entries (P1 and P2 in watts) or two Voltage entries (V1 and V2 in Volts). A reference resistance (Rref = 50 ohms default) relates the Voltage and Power entries. For plain db ratio expression, db = 10 * log(P1/P2) or db = 20 * log(V1/V2). For dbm absolute power expression, P2 is fixed at .001 Watts (1 milliWatt) and V2 is set the square root of P2*Rref or 0.2236 Volts RMS for a 50 ohm reference.

Radio buttons select whether you calculate dbm (the default) or db. Special text fields are displayed for the db value, V1, V2, P1 and P2 parameters. DB, V and P buttons copy the calculator text field entry to the DB, V1 or P1 text field and computation is updated. To copy entries into V2 or P2 text fields, first press the V2P2 button and then press the V or P button as appropriate.

Voltage entries are expressed in Volts RMS (root mean squared). For a sine wave signal, Vrms = Vpeak / SQRT(2) or Vrms = 0.707 * Vpeak. For peak to peak values Vpp, Vrms = 0.3535 * Vpp.

Exponential App

The Exponential App solves the RC time constant equation V = Vfinal - (Vfinal - Vinitial) e**(t / (R * C)) or the RL time constant equation V = Vfinal - (Vfinal - Vinitial) e**(t / (L / R)) as selected by radio buttons.

Resonant Frequency App

The Resonant Frequency App solves the frequency equation F = 1 / (2 * PI * SQRT(L * C)); The values are scaled to typical units so you specify frequency in Megahertz, Inductance in micro-Henries and capacitance in pico-Farads. Resistance R can be specified in Ohms which results in Q and bandwidth figures calculated.

Toroid Design App

The Toroid Design App solves the number of turns of wire needed to get a specific inductance. You specify inductance, AC and DC current, core size, core material, wire size and frequency of operation. The number of turns is calculated. A RND button rounds the estimate to the nearest integer turn value. Physical limits of the number of turns possible for a single layer winding and wire current capability are presented to show design margin. Estimates of power dissipation due to wire loss and core loss are estimated as well as free standing temperature rise and flux density. Estimate accuracy is very rough due to insufficient data on core material properties, but they can indicate areas where further investigation is required. A detailed report of the design is shown in a text area at the bottom of the calculator. For more information read QuickApp Toroid Design.

You can also design a Transmission Line Transformer (TLT) using a toroid. A TLT is a 1:1 transformer made from a toroid wound with a twisted pair wire. Select the "TL xfmr" radio button then specify the minimum frequency (-3db point) for the transformer and the AC and DC currents expected. The design report shows the design and maximum limits. Adjust wire size, core material and core size to meet your requirements.

Air Core Inductor App

The Air Core Inductor App solves the air core, solenoid inductor equation L(uH) = d**2 * n**2 / (18d + 40 * length); The values are scaled to typical units so you specify Inductance in micro-Henries and dimensions in inches or centimeters. Frequency F can be specified in MHz which results in Q and impedance being calculated. The parameter Turns Per Inch can be a variable or constant. Checks are performed to ensure the design is realizable.

Impedance Matching App

The Impedance Matching App designs an LC network to match circuits of different resistances. Select between PI, L or LCC networks.

RF Filter App

The RF Filter App designs a Butterworth or Chebyshev filter in either Low Pass, High Pass, Band Pass or Band Stop configurations. You specify the output impedance, filter 3 db frequency and filter order. Choose series or shunt configurations and the report lists L and C component values along with a picture of the circuit configuration. You can get a report of attenuation at a specified frequency.

RF Field (EMI) App

The RF Field App estimates the E field created by an RF power source or current loop. The effects of a shielding enclosure with holes can be examined. The report field indicates if FCC Part 15 or safety limits are exceeded.

Receiver Analysis App

The Receiver Analysis App analyzes noise, gain and dynamic range for a single conversion analog or digital receiver. You select the elements of the receive path, edit the element's specifications and view the analysis report. The design elements include filters, amplifiers, attenuator, mixer and A/D converter. The report field summarizes the design and indicates S/N, Noise Figure, dynamic range and input signal capabilities.

Active Filter Synthesis App

The Active Filter Synthesis App provides resistor and capacitor values for active filters using op amps. Make low pass, high pass, band pass or band stop filters. You specify the cut-off or center frequency and bandwidth plus a standard capacitor value. The report summarizes all parameters. Verify the design separately in Spice.

Capacitor Calculator

The Capacitor Calculator lets you determine capacitance for parallel plate or cylindrical types. Specify the physical parameters and dielectric material. A detailed report summarizes the results.

Loop Antenna Analysis

Calculate various parameters for a small, magnetic loop antenna. A detailed report summarizes the results.

Discovery (eo servers)

The Discovery tool finds active eightolives Microservers on your local network by scanning for specified parameters. Servers found are listed as hyperlinks.

Schematic Mobile

Schematic Mobile is a graphical design entry tool that lets you create schematics and symbols. You can generate design reports, netlists in gEDA or PADS format and VHDL. Simulatable models and templates can be created from the schematic or symbols.


WaveformViewer lets you create timing diagrams and simulate digital circuits. Waveforms can be saved and read as Value Change Dump (VCD) files. Simulation models and templates are created from Schematic Mobile.


Editor lets you edit design document templates and create various reports relating to requirements and status.